A rapid detection method for trace chlorine ions in synthetic silica and application thereof

Abstract

The application discloses a rapid detection method for trace chlorine ions in synthetic silicon dioxide and application thereof. The rapid detection method for trace chlorine ions in synthetic silicon dioxide comprises the following processes: cleaning a dissolving tank, preparing a sample solution, preparing a standard chlorine ion solution, detecting by ion chromatography, analyzing test results and determining chlorine ion content in synthetic silicon dioxide. The method has the advantages of easy operation, short time consumption, high measurement precision, accurate content determination and the like, and simultaneously prevents chlorine ions and solvent volatilization without additional addition of a cosolvent, and provides an important sample processing and detection means for determination of chlorine ion concentration in ultrahigh-purity synthetic silicon dioxide.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of trace chlorine ion detection, and particularly relates to a rapid detection method for trace chlorine ions in synthetic silicon dioxide and application thereof. BACKGROUND

[0002] Silicon dioxide (SiO2) is an inorganic compound with hardness, high temperature resistance, corrosion resistance and stable chemical properties, and is widely used in glass, optical fiber, silicone resin and semiconductor fields. In particular, ultra-high purity SiO2 is a key basic material for high-tech industries such as semiconductors, photovoltaics and cutting-edge optics, and has an important strategic position. Among them, SiO2 prepared by chemical synthesis method with silicon-containing compounds as raw materials has higher purity than purified SiO2, and is the most promising means to meet the demand for ultra-high purity SiO2 in related industries in the future.

[0003] The main chemical synthesis method at present stage is to use chlorosilane as raw material to directly generate in hydrogen-oxygen flame or to react with water or alcohol in liquid phase to generate an intermediate, and then to obtain SiO2 powder through subsequent treatment. Due to the presence of chlorine in the raw material, SiO2 generated by the above method will inevitably have a certain amount of chlorine ions remaining, and the remaining chlorine ions may cause corrosion and other adverse effects of the product. Especially when used to manufacture semiconductor and photovoltaic crucibles, trace amounts of chlorine ion impurities, generally in ppm level, may cause crucible crystallization, bubble generation, and even escape during long-term high-temperature use to affect product quality. Therefore, accurate quantification of trace chlorine ion impurities in SiO2 is particularly important.

[0004] At present, there is no corresponding standard method for the analysis and detection of trace chlorine ions in SiO2 in China. The relevant literature and patent technical solutions that can be consulted mainly include four methods: silver nitrate colorimetric method, chlorine ion selective electrode method, mercury salt titration method and ion chromatography method. Among them, the silver nitrate colorimetric method and the mercury salt titration method not only use toxic chemical reagents but also have low detection precision, and cannot meet the accurate determination of chlorine ions in ultra-high purity SiO2. Compared with the chlorine ion selective electrode method, the ion chromatography method has a lower detection limit and a smaller relative error

Document 1

[0005] Although ion chromatography has been used for the detection of chloride ions, the detection objects are mainly solutions or solid leaching solutions

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Literature 1

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[0009]

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Literature 5

[0011]

Literature 6

[0012] In view of the above technical problems and the deficiencies in the art, the present application provides a rapid detection method for trace chloride ions in synthetic silica and its application. The present application is a rapid detection technology for trace chloride ions in insoluble solids, especially a technology for determining the concentration of trace chloride ions in synthetic silica by ion chromatography.

[0013] The present application is devoted to the preparation of sample solution by means of simple heating of alkaline solution to completely dissolve synthetic silica, and then accurate determination of chloride ion content in synthetic silica by ion chromatography. Through the foregoing technical method, the use of complex reagents is avoided, the operation process is simplified, the time consumption is short, and rapid and high-precision detection of chloride ions is realized.

[0014] The present application is devoted to the preparation of sample solution by means of simple heating of alkaline solution to completely dissolve synthetic silica, and then accurate determination of chloride ion content in synthetic silica by ion chromatography. Through the foregoing technical method, the use of complex reagents is avoided, the operation process is simplified, the time consumption is short, and rapid and high-precision detection of chloride ions is realized.

[0015] The specific technical solutions are as follows:

[0016] A rapid detection method for trace chloride ions in synthetic silica, comprising:

[0017] Cleaning the sample dissolving tank: before dissolving synthetic silica in the sample dissolving tank each time, sequentially perform ultrasonic cleaning, high-temperature acid washing, high-temperature water washing and drying operation on the sample dissolving tank; the material of the sample dissolving tank is polytetrafluoroethylene PFA; the ultrasonic cleaning time is 5-10 minutes, and the sample dissolving tank is filled with water during the ultrasonic cleaning; the high-temperature acid washing temperature is 125-135℃ (preferably 130℃), the time is 180-200 minutes, and the acid washing solution used is a mixed solution of nitric acid and water with a volume ratio of 0.5-1:1; the high-temperature water washing temperature is 125-135℃ (preferably 130℃), and the time is 180-200 minutes; the volume of the acid washing solution used in the high-temperature acid washing and the water used in the high-temperature water washing is not less than 2 / 3 of the volume of the sample dissolving tank;

[0018] Preparation of sample solution: accurately weigh synthetic silica and place it in the cleaned sample dissolving tank, add an alkaline aqueous solution, and seal and heat to digest to obtain a colorless and clear sample solution; the sealing and heating digestion temperature is 100-120℃, and the time is 20-180 min, for example, 40 min, 60 min, 100 min, etc.;

[0019] Preparation of standard chloride ion solution: prepare multiple standard chloride ion solutions with the same volume and a certain concentration gradient;

[0020] Ion chromatography detection: use ion chromatography to determine the prepared sample solution and standard chloride ion solution, and record the characteristic peak area of chloride ions;

[0021] Analysis test result: the standard curve graph is drawn by using the characteristic peak area of chloride ion of standard chloride ion solution and the corresponding chloride ion concentration, and the equation of the characteristic peak area of chloride ion and the chloride ion concentration is obtained by linear fitting as follows: S'=a+bxC, wherein: S' represents the characteristic peak area of chloride ion (the unit can be μs·min), and the characteristic peak area of chloride ion S' is the value after deducting the background peak area, the background peak area is the characteristic peak area of chloride ion measured by the standard chloride ion solution with 0 ppm of chloride ion, C is the chloride ion concentration (the unit can be mg / L) of the standard chloride ion solution, and a and b are standard curve fitting constants;

[0022] Determine the chloride ion content in the synthetic silica:

[0023] Calculate the actual chloride ion characteristic peak area S of the sample solution: S=S1-S0, wherein: S1 represents the chloride ion characteristic peak area of the sample solution (the unit can be μs·min), and S0 represents the chloride ion characteristic peak area of the blank solution (the unit can be μs·min); the difference between the blank solution and the sample solution is only that no synthetic silica is added in the blank solution, and the rest are the same;

[0024] Substitute the actual chloride ion characteristic peak area of the sample solution into the equation S'=a+bxC obtained by fitting to obtain the chloride ion concentration in the sample solution;

[0025] According to the chloride ion concentration in the sample solution, the chloride ion content in the synthetic silica is calculated.

[0026] The inventors found in the research process that the PFA material of the sample dissolving tank is transparent, which facilitates observation of whether the synthetic silica is completely digested, but if the PFA material is not sufficiently cleaned during repeated use and detection, impurities will affect the accuracy of the determination of trace chloride ions. These impurities may be derived from residues of raw materials, medicines and other substances in the digestion process. It is found that simple water washing cannot completely clean the impurities. If hydrofluoric acid is used, fluorine ions are difficult to remove, which will interfere with subsequent ion chromatography detection, and hydrochloric acid will introduce chloride ions, which will further increase the determination error of chloride ions. Based on this, the application proposes that the sample dissolving tank is treated by ultrasonic cleaning, high-temperature acid washing and high-temperature water washing with specific requirements and parameter conditions in sequence before each use, so as to avoid the influence of impurities.

[0027] Subsequently, the application realizes rapid (not more than 3 h) heating and dissolution of the synthetic silica powder in the sample dissolving tank under the action of an alkaline solution, and prepares a clear liquid sample.

[0028] In addition, the present application also adopts the data processing means of deducting the background peak, draws the corresponding standard curve, and solves the problem of inaccurate low content value caused by the area of the background peak. The present application research finds that if the data processing means of deducting the background peak is not adopted, when multiple standard chloride ion solutions are prepared by using NaOH solution with different pH for gradient dilution, and the corresponding standard curve is drawn by using these standard chloride ion solutions, the chloride ion concentration of the same sample calculated according to these standard curves is quite different, which leads to the inaccurate trace chloride ion in the final detection of synthetic silicon dioxide.

[0029] In summary, the method of the present application not only prevents the volatilization of chloride ion and solvent, but also does not need to add additional cosolvent, has the advantages of easy operation, short time consumption, high measurement precision and accurate content determination, and provides an important sample processing and detection means for the determination of the concentration of chloride ion in ultra-high purity synthetic silicon dioxide.

[0030] In some embodiments, the rapid detection method of trace chloride ion in synthetic silicon dioxide, the volume of the sample dissolving tank can be 60-80 mL.

[0031] In some embodiments, the rapid detection method of trace chloride ion in synthetic silicon dioxide, the alkaline aqueous solution can be a sodium hydroxide aqueous solution, the concentration of sodium hydroxide in the sodium hydroxide aqueous solution can be 0.2-1 mol / L, further can be 0.5-1 mol / L, for example, 0.4 mol / L, 0.8 mol / L, etc., the amount of the alkaline aqueous solution can be 30%-45% of the volume of the sample dissolving tank (for example, the amount of the alkaline aqueous solution can be 20-25 mL, etc.), the ratio of the added mass of synthetic silicon dioxide in the sample dissolving tank to the volume of the alkaline aqueous solution is (0.45-0.60 g):(20-25 mL).

[0032] In some embodiments, the rapid detection method of trace chloride ion in synthetic silicon dioxide, after the sealed heating digestion obtains a colorless and clear sample solution, the sample solution is cooled to room temperature, filtered by a 0.22 micron nylon filter membrane, the first 2-3 mL of filtrate is discarded, and the remaining filtered sample solution is used for ion chromatography detection.

[0033] In some embodiments, the rapid detection method of trace chloride ion in synthetic silicon dioxide, the synthetic silicon dioxide can be hydrophilic silicon dioxide and / or hydrophobic silicon dioxide.

[0034] In some embodiments, the rapid detection method of trace chloride ion in synthetic silicon dioxide, multiple standard chloride ion solutions with the same volume and a certain concentration gradient can be obtained by gradient dilution with NaOH solution.

[0035] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the preparation of a plurality of standard chloride ion solutions with the same volume and a concentration gradient can specifically include: diluting a standard chloride ion solution with a chloride ion concentration of 50 μg / mL (ppm) with a NaOH solution in a gradient to obtain a plurality of standard chloride ion solutions with a chloride ion concentration gradient of 0-5 mg / L and the same volume. For example, 10 mL, 6 mL, 2 mL, 1 mL, 0.6 mL, 0.2 mL and 0 mL of 50 μg / mL (ppm) standard chloride ion solution can be accurately measured respectively in a 100 mL volumetric flask, and the volume can be made up with a NaOH solution, and after shaking, standard chloride ion solutions with different concentrations can be prepared.

[0036] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the pH of the NaOH solution can be 11.5-12.5.

[0037] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the pH of the sample solution for ion chromatography detection can be 11-13, and further can be 11.5-12.5.

[0038] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the ion chromatography detection can be performed using an ion chromatograph, specifically: the sample solution and the standard chloride ion solution can be respectively injected into the ion chromatograph through the injection needle, the ion chromatograph test program can be started, and a corresponding chromatogram curve can be obtained after waiting for a period of time, and the chloride ion characteristic peak area can be recorded.

[0039] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the ion chromatography test conditions can include: assembling a anion suppressor, the suppressor type is AERS-4 mm, and the suppressor current is 50 mA; using AS19 separation column and AG19 guard column, the column type is 4 mm × 250 mm; the eluent is 50 mmol / L KOH solution; the column oven temperature is 30℃; and the injection amount is 25 μL.

[0040] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the standard curve graph can take the chloride ion characteristic peak area of the standard chloride ion solution as the ordinate and the chloride ion concentration as the abscissa.

[0041] In some embodiments, the method for rapid detection of trace chloride ions in synthetic silica, the calculation of the chloride ion content in synthetic silica according to the chloride ion concentration in the sample solution can specifically include:

[0042] The chloride ion content in the synthetic silica is calculated by substituting the chloride ion concentration in the sample solution into the following formula: w = c x v / M / 1000, wherein: w represents the chloride ion content in the synthetic silica, in mg / Kg (ppm), c represents the chloride ion concentration in the sample solution, in mg / L, v represents the sample solution volume, in L, and M represents the mass of the synthetic silica, in g.

[0043] The application further provides application of the rapid detection method in rapid detection of trace chloride ions in synthetic silica.

[0044] Preferably, all the chemical reagents used in the application are of superior grade or above, and the water used is 18.2 mega-ohm grade ultrapure water.

[0045] In the application, the equation S' = a + b x C obtained by fitting is regarded as an effective working curve when the linear coefficient is 0.999 or above.

[0046] The application aims to realize rapid and high-precision detection of trace chloride ions in synthetic SiO2 at a lower detection lower limit without using complex reagents. The synthetic SiO2 is rapidly dissolved in a closed sample dissolving tank by heating an alkaline aqueous solution, so as to solve the problems of incomplete release of trace chloride ions in synthetic SiO2, interference of a dissolution aid and possible overflow of chloride ions.

[0047] Compared with the prior art, the application has the following beneficial effects:

[0048] (1) The sample dissolving tank is sequentially subjected to ultrasonic cleaning, high-temperature acid washing and high-temperature water washing before dissolution in the application, so as to avoid errors caused by the introduction of impurities.

[0049] (2) The synthetic SiO2 is completely dissolved in a short time by heating a sodium hydroxide solution in a closed PFA material sample dissolving tank without adding a dissolution aid in the application, so as to avoid the influence caused by the additional addition of a dissolution aid, overcome the problem of possible volatilization of chloride ions in the digestion process, omit the pH adjusting step, and make the operation more simple and fast.

[0050] (3) The influence of the background peak is deducted when the standard curve is drawn in the application, so as to solve the problem of inaccurate low content values caused by the background peak area. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 The chloride ion concentration standard curve after deduction of the background (pH = 12.5).

[0052] Figure 2 The ion chromatogram of Example 1.

[0053] Figure 3 The ion chromatogram of Example 2.

[0054] Figure 4 Standard curve of chloride ion concentration after background deduction (pH = 11.5).

[0055] Figure 5 Ion chromatogram of Example 3.

[0056] Figure 6 Standard curve of chloride ion concentration without background deduction (pH = 12.5).

[0057] Figure 7 Ion chromatogram of Example 5.

[0058] Figure 8 Ion chromatogram of Example 6.

[0059] Figure 9 Ion chromatogram of Example 7.

[0060] Figure 10 Ion chromatogram of Example 8.

[0061] Figure 11 Ion chromatogram of Example 9.

[0062] Figure 12 Standard curve of chloride ion concentration without background deduction (pH = 11.5).

[0063] Figure 13 Ion chromatogram of Example 11. DETAILED DESCRIPTION

[0064] The application will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. The operation methods in the following examples without specific conditions are usually according to the conventional conditions or the conditions suggested by the manufacturers.

[0065] In the following examples, the volume of the sample dissolving tank is 60 mL and the material is polytetrafluoroethylene PFA unless otherwise specified. Example 1

[0066] 1) Cleaning of the sample dissolving tank: fill the sample dissolving tank with water and ultrasonic for 5 minutes, pour out and add 40 mL of nitric acid aqueous solution (volume ratio of nitric acid to water is 1:1), keep at 130℃ for 3 h, pour out the nitric acid aqueous solution and add 40 mL of water to continue keeping at 130℃ for 3 h, and finally dry for standby.

[0067] 2) Preparation of sample solution: 8 g of NaOH was accurately weighed and diluted to a 250 mL volumetric flask with ultrapure water to obtain a 0.8 mol / L NaOH solution. The synthetic Si02 powder numbered S-1 (hydrophilic, specific surface area 150 m 2 / g, particle size 7-40 nm) was weighed using an analytical balance. The weighed Si02 powder was placed in a high-temperature-resistant sample dissolving tank, 20 mL of NaOH solution was measured in a reagent bottle, tightly sealed, and placed on a constant temperature heating table at 100°C for 30 min. After cooling to room temperature, 12 mL of the solution was removed using a sterile injection solution, filtered through a 0.22 μm nylon filter, and the first 2 mL of the filtrate was discarded. The filtered solution was stored in a PFA bottle. The above method obtained a sample solution to be tested with a pH value of 12.4 at 25°C. The solution prepared without Si02 powder sample at the same pH was the blank solution.

[0068] 3) Preparation of standard chloride solution: 10 mL, 6 mL, 2 mL, 1 mL, 0.6 mL, 0.2 mL and 0 mL of 50 μg / mL (ppm) standard chloride solution were accurately measured into a 100 mL volumetric flask, and diluted to the mark with NaOH aqueous solution with pH=12.5, shaken to prepare standard solutions with chloride ions of 5 ppm, 3 ppm, 1 ppm, 0.5 ppm, 0.3 ppm, 0.1 ppm and 0 ppm, respectively.

[0069] 4) Ion chromatography detection: The solutions in steps 1) and 2) were detected by ion chromatography. The technical conditions of the ion chromatography are as follows: equipped with anion suppressor, suppressor type AERS-4 mm, suppressor current 50 mA; AS19 separation column and AG19 guard column, column type 4 mm × 250 mm; eluent 50 mmol / L KOH solution; column oven temperature 30°C; sample size 25 μL.

[0070] The measured chloride ion concentration and the corresponding characteristic peak area are shown in Tables 1 and 2. Figure 2 The ion chromatography detection results of the sample solution to be tested (a) and the blank sample (b) of this example are shown.

[0071] Table 1 Standard chloride ion concentration and peak area

[0072]

[0073] Table 2 Peak area of sample solution

[0074]

[0075] 5) Test result analysis: with standard chloride ion concentration as the horizontal coordinate and peak area as the vertical coordinate, a chloride ion standard solution curve is drawn as shown in Figure 1 , and the fitting equation is shown in Equation 1.

[0076] S' / (μs·min) = 0.00412 + 0.2717 × C / (mg / L) Equation 1

[0077] wherein S' represents the chloride ion characteristic peak area after deducting the background, C is the chloride ion concentration of the standard solution, and the linear coefficient is 0.9993.

[0078] 6) Chlorine concentration calculation in the sample to be tested:

[0079] Firstly, the actual chloride ion characteristic peak area S in the sample solution to be tested is calculated by using Equation 2:

[0080] S / (μs·min) = S1– S0 Equation 2

[0081] wherein S1represents the chloride ion characteristic peak area of the sample, and S0represents the chloride ion characteristic peak area of the blank solution.

[0082] The peak area 0.354 of the sample and the peak area 0.112 of the blank solution are substituted into Equation 2 to calculate the peak area 0.242 in the sample S-1. Subsequently, the peak area of S-1 is substituted into Equation 1 to obtain the concentration c of the chloride ion in the sample solution, which is 0.8755 mg / L.

[0083] Finally, the concentration is substituted into the following formula to calculate the chloride ion content w,

[0084] w = c×v / M / 1000 Equation 3

[0085] wherein:

[0086] w – SiO2chloride ion content (ppm);

[0087] c – chloride ion concentration in the sample solution (mg / L);

[0088] v – volume of the liquid to be tested (L);

[0089] M – mass of SiO2(g);

[0090] The sample mass 0.512 g and the volume of the liquid to be tested 20 mL are substituted into Equation 3 to calculate the chloride ion content in the sample S-1, which is 34.20 ppm. Example 2

[0091] 1) Cleaning of the sample dissolving tank: this part is consistent with Example 1.

[0092] 2) Preparation of sample solution: 2 g of NaOH was accurately weighed and diluted to a 250 mL volumetric flask with ultrapure water to obtain a 0.2 mol / L NaOH solution. The synthetic SiO2 powder numbered S-1 was weighed using an analytical balance. The weighed SiO2 powder was placed in a high-temperature-resistant sample dissolving tank, 20 mL of the NaOH solution was measured into the sample dissolving tank, which was tightly sealed and placed on a constant temperature heating table at 120°C for 20 min. After taking out, it was cooled to room temperature, 13 mL of the solution was removed using a sterile injection solution, filtered through a 0.22 μm nylon filter, the first 2 mL of the filtrate was discarded, and the filtered solution was stored in a PFA bottle. The above method obtained a sample solution to be tested with a pH value of 11.4 at 25°C. The solution prepared without adding SiO2 powder sample was a blank solution at the same pH.

[0093] 3) Preparation of standard chloride ion solution: 10 mL, 6 mL, 2 mL, 1 mL, 0.6 mL, 0.2 mL and 0 mL of 50 μg / mL (ppm) standard chloride ion solution were accurately measured into a 100 mL volumetric flask, and diluted to the mark with NaOH aqueous solution with pH = 11.5, and shaken to prepare standard solutions with chloride ions of 5 ppm, 3 ppm, 1 ppm, 0.5 ppm, 0.3 ppm, 0.1 ppm and 0 ppm, respectively.

[0094] 4) Ion chromatography detection: the instrument parameter settings were consistent with those of Example 1, and the measured chloride ion concentration and corresponding characteristic peak area are shown in Tables 3 and 4. Figure 3 The ion chromatography detection results of the sample solution to be tested (a) and the blank sample (b) of this example are shown.

[0095] Table 3 Standard chloride ion concentration and peak area

[0096]

[0097] Table 4 Peak area of sample solution

[0098]

[0099] 5) Test result analysis: the standard chloride ion concentration was taken as the abscissa, and the peak area was taken as the ordinate, and the chloride ion standard solution curve was drawn as Figure 4 , and the fitting equation is shown in formula 4;

[0100] S' / (μs·min) = -0.011 + 0.2691 × C / (mg / L) Formula 4

[0101] Wherein, S' represents the area of chloride ion characteristic peak after deducting background, C is the concentration of chloride ion in standard solution, and the linear coefficient is 0.9995.

[0102] 6) Chlorine concentration calculation in the sample to be measured: first, the sample peak area 0.285 and the blank solution peak area 0.026 are substituted into formula 2 to calculate the peak area of S-1 sample as 0.259. Then, the peak area of S-1 is substituted into formula 4 to obtain the concentration of chloride ion in the corresponding sample solution as 1.0033 mg / L. Finally, the sample mass 0.595 g and the volume of the liquid to be measured 20 mL are substituted into formula 3 to calculate the content of chloride ion in S-1 sample as 33.72 ppm. Example 3

[0103] 1) Cleaning of the sample dissolving tank: this part is consistent with example 1.

[0104] 2) Preparation of the sample solution: accurately weigh 5 g of NaOH, and dilute to a 250 mL volumetric flask with ultrapure water to obtain a 0.5 mol / L NaOH solution. Weigh the synthetic SiO2 powder numbered S-1 using an analytical balance. Place the weighed SiO2 powder in a high-temperature-resistant sample dissolving tank, and measure 20 mL of NaOH solution into the sample dissolving tank, tightly seal and screw, and place it on a constant temperature heating table at 120°C for 30 min. After taking it out, cool it to room temperature, use a sterile injection liquid to remove 12 mL of solution, filter it through a 0.22 μm nylon filter, discard the first 2 mL of filtrate, and store the filtered solution in a PFA bottle. The above method obtains a sample solution to be measured with a pH value of 12.06 at 25°C. The solution prepared without adding SiO2 powder sample is the blank solution under the same pH.

[0105] 3) Ion chromatography detection: the instrument parameter settings are consistent with example 1, and the measured chloride ion concentration and the corresponding characteristic peak area are shown in Table 5. Figure 5 The ion chromatography detection results of the sample solution to be measured (a) and the blank sample (b) of this example are shown.

[0106] Table 5 Peak area of sample solution

[0107]

[0108] 4) Calculation of the chlorine concentration in the sample to be tested: first, the sample peak area 0.285 and the blank solution peak area 0.085 are substituted into formula 2 to calculate the peak area of the S-1 sample, which is 0.242. Then, the peak area of S-1 is substituted into formula 1 to obtain the concentration of chlorine ions in the corresponding sample solution, which is 0.8755 mg / L. Finally, the sample mass 0.500 g and the volume of the sample solution 20 mL are substituted into formula 3 to calculate the chlorine ion content in the S-1 sample, which is 35.02 ppm. Example 4

[0109] 1) Cleaning of the sample dissolving tank: this part is consistent with Example 1.

[0110] 2) Preparation of the sample solution: this part is consistent with Example 1.

[0111] 3) Preparation of the standard chlorine ion solution: this part is consistent with Example 1.

[0112] 4) Ion chromatography detection: this part is consistent with Example 1. The measured chlorine ion concentration and the corresponding characteristic peak area are shown in Table 1 and Table 6.

[0113] Table 6 Peak area of the sample solution

[0114]

[0115] 5) Analysis of the test results: the chlorine ion standard solution curve is plotted with the standard chlorine ion concentration as the abscissa and the peak area as the ordinate Figure 6 , and the fitting equation is shown in formula 5;

[0116] S' / (μs·min) = 0.11612 + 0.2717 × C / (mg / L) Formula 5

[0117] wherein S' represents the characteristic peak area of chlorine ions, C is the chlorine ion concentration of the standard solution, and the linear coefficient is 0.9993.

[0118] 6) Calculation of the chlorine concentration in the sample to be tested: first, the sample peak area 0.354 and the blank solution peak area 0.112 are substituted into formula 2 to calculate the peak area of the S-1 sample, which is 0.242. Then, the peak area of S-1 is substituted into formula 5 to obtain the concentration of chlorine ions in the corresponding sample solution, which is 0.4633 mg / L. Finally, the sample mass 0.512 g and the volume of the sample solution 20 mL are substituted into formula 3 to calculate the chlorine ion content in the S-1 sample, which is 18.09 ppm. Example 5

[0119] 1) Cleaning of the sample dissolving tank: the sample dissolving tank is filled with water and ultrasonicated for 5 minutes, then cleaned several times with ultrapure water, and finally dried for standby use.

[0120] 2) Preparation of sample solution: This part is consistent with Example 1.

[0121] 3) Preparation of standard chloride solution: This part is consistent with Example 1.

[0122] 4) Ion chromatography detection: This part is consistent with Example 1, and the measured chloride concentration and the corresponding characteristic peak area are shown in Table 7. Figure 7 The ion chromatography detection results of the sample solution (a) to be tested and the blank sample (b) of this example are shown.

[0123] Table 7 Peak area of sample solution

[0124]

[0125] 5) Calculation of chlorine concentration in the sample to be tested: First, the sample peak area 0.368 and the blank solution peak area 0.021 are substituted into formula 2 to calculate the peak area of S-1 sample as 0.347. Then, the peak area of S-1 is substituted into formula 1 to obtain the corresponding concentration of chloride ions in the sample solution as 1.015 mg / L. Finally, the sample mass 0.518 g and the volume of the liquid to be tested 20 mL are substituted into formula 3, and the calculated chloride ion content in S-1 sample is 39.20 ppm. Example 6

[0126] 1) Cleaning of sample dissolving tank: This part is consistent with Example 1.

[0127] 2) Preparation of sample solution: 2 g of NaOH was accurately weighed and diluted to a 250 mL volumetric flask with ultrapure water to obtain a 0.2 mol / L NaOH solution. The synthetic SiO2 powder (hydrophilic, specific surface area 380 m 2 / g, particle size 7-40 nm) numbered S-2 was weighed using an analytical balance. The weighed SiO2 powder was placed in a high-temperature-resistant sample dissolving tank, 24 mL of NaOH solution was measured into the sample dissolving tank, which was tightly sealed and placed on a constant temperature heating table at 120°C for 20 min. After cooling to room temperature, 12.4 mL of solution was removed using a sterile injection solution, filtered through a 0.22 μm nylon filter, and the first 2 mL of filtrate was discarded. The filtered solution was stored in a PFA bottle. The above method obtained a sample solution to be tested with a pH value of 11.4 at 25°C. The solution prepared without SiO2 powder sample under the same pH was a blank solution.

[0128] 3) Ion chromatography detection: The instrument parameter settings are consistent with Example 1, and the measured chloride ion concentration and the corresponding characteristic peak area are shown in Table 8. Figure 8The ion chromatography detection results of the sample solution (a) and the blank sample (b) of this example are shown.

[0129] Table 8 Peak area of sample solution

[0130]

[0131] 4) Calculation of the chlorine concentration in the sample: first, the sample peak area 0.308 and the blank solution peak area 0.112 are substituted into formula 2 to calculate the peak area of the S-2 sample as 0.196. Then, the peak area of S-2 is substituted into formula 4 to obtain the concentration of chlorine ions in the corresponding sample solution as 0.7692 mg / L. Finally, the sample mass 0.522 g and the volume of the sample solution 24 mL are substituted into formula 3 to calculate the chlorine ion content in the S-2 sample as 35.36 ppm. Example 7

[0132] 1) Cleaning of the sample dissolving tank: this part is consistent with Example 1.

[0133] 2) Preparation of the sample solution: accurately weigh 8 g of NaOH, and dilute to a 250 mL volumetric flask with ultrapure water to obtain a 0.8 mol / L NaOH solution. Weigh the synthetic SiO2 powder (hydrophobic, specific surface area 115 m 2 / g, particle size 7-40 nm) numbered S-3 using an analytical balance. Place the weighed SiO2 powder in a high-temperature-resistant sample dissolving tank, and measure 20 mL of the NaOH solution into the sample dissolving tank, and tightly seal and screw. Place it on a constant temperature heating table at 100°C for 60 min, and then take it out. Cool to room temperature, use a sterile injection liquid to remove 12 mL of the solution, filter it through a 0.22 μm nylon filter, discard the first 2 mL of the filtrate, and store the filtered solution in a PFA bottle. The above method obtains a sample solution to be tested with a pH value of 12.55 at 25°C. The solution prepared without adding SiO2 powder sample is the blank solution at the same pH.

[0134] 3) Ion chromatography detection: the instrument parameter settings are consistent with Example 1, and the measured chlorine ion concentration and the corresponding characteristic peak area are shown in Table 9. Figure 9 The ion chromatography detection results of the sample solution (a) and the blank sample (b) of this example are shown.

[0135] Table 9 Peak area of sample solution

[0136]

[0137] 4) Chlorine concentration calculation in the sample: first, the sample peak area 0.376 and the blank solution peak area 0.112 are substituted into formula 2, and the peak area of sample S-3 is calculated to be 0.264. Then, the peak area of S-3 is substituted into formula 1, and the concentration of chlorine ions in the corresponding sample solution is calculated to be 0.9565 mg / L. Finally, the sample mass 0.506 g and the volume of the sample solution 20 mL are substituted into formula 3, and the chlorine ion content in sample S-3 is calculated to be 37.81 ppm. Example 8

[0138] 1) Cleaning of the sample dissolving tank: this part is consistent with Example 1.

[0139] 2) Preparation of the sample solution: accurately weigh 4 g of NaOH, and dilute to 250 mL with ultrapure water to obtain a 0.4 mol / L NaOH solution. Weigh the synthetic Si02 powder numbered S-3 using an analytical balance. Place the weighed Si02 powder in a high-temperature-resistant sample dissolving tank, and measure 20 mL of the NaOH solution into the sample dissolving tank. Seal and tighten, and place it on a constant temperature heating table at 120°C for 40 min. After taking it out, cool it to room temperature, use a sterile injection solution to transfer 13 mL of the solution, filter it through a 0.22 μm nylon filter, discard the first 2 mL of the filtrate, and store the filtered solution in a PFA bottle. The above method obtains a sample solution to be tested with a pH value of 11.63 at 25°C. The solution prepared without adding Si02 powder sample is the blank solution.

[0140] 3) Ion chromatography detection: the instrument parameter settings are consistent with Example 1, and the measured chlorine ion concentration and the corresponding characteristic peak area are shown in Table 10. Figure 10 The ion chromatography detection results of the sample solution to be tested (a) and the blank sample (b) of this example are shown.

[0141] Table 10 Peak area of sample solution

[0142]

[0143] 4) Chlorine concentration calculation in the sample: first, the sample peak area 0.376 and the blank solution peak area 0.112 are substituted into formula 2, and the peak area of sample S-3 is calculated to be 0.264. Then, the peak area of S-3 is substituted into formula 4, and the concentration of chlorine ions in the corresponding sample solution is calculated to be 0.9848 mg / L. Finally, the sample mass 0.506 g and the volume of the sample solution 20 mL are substituted into formula 3, and the chlorine ion content in sample S-3 is calculated to be 38.92 ppm. Example 9

[0144] 1) Cleaning of the sample dissolving tank: this part is consistent with Example 1.

[0145] 2) Preparation of sample solution: 2 g of NaOH was accurately weighed and diluted to 250 mL volumetric flask with ultrapure water to obtain 0.2 mol / L NaOH solution. The synthetic Si02 powder numbered S-3 was weighed using an analytical balance. The weighed Si02 powder was placed in a high-temperature-resistant sample dissolving tank, 20 mL of NaOH solution was measured into the sample dissolving tank, tightly sealed, and placed on a constant temperature heating table at 120°C for 120 min and then taken out. After cooling to room temperature, 13 mL of the solution was removed using a sterile injection solution, filtered through a 0.22 μm nylon filter, the first 2 mL of filtrate was discarded, and the filtered solution was stored in a PFA bottle. The above method obtained a sample solution to be tested with a pH value of 11.48 at 25°C. A solution prepared without adding Si02 powder sample was a blank solution at the same pH.

[0146] 3) Ion chromatography detection: the instrument parameter settings were consistent with those of Example 1, and the measured chloride ion concentration and the corresponding characteristic peak area are shown in Table 11. Figure 11 The ion chromatography detection results of the sample solution to be tested (a) and the blank sample (b) of this example are shown.

[0147] Table 11 Peak area of sample solution

[0148]

[0149] 4) Calculation of chloride concentration in the sample to be tested: first, the sample peak area 0.296 and the blank solution peak area 0.032 are substituted into formula 2 to calculate the peak area of S-3 sample as 0.264. Then, the peak area of S-3 is substituted into formula 4 to obtain the corresponding chloride ion concentration in the sample solution as 1.022 mg / L. Finally, the sample mass 0.518 g and the test liquid volume 20 mL are substituted into formula 3 to calculate the chloride ion content in S-3 sample as 39.46 ppm. Example 10

[0150] 1) Cleaning of sample dissolving tank: this part is consistent with Example 1.

[0151] 2) Preparation of sample solution: this part is consistent with Example 8.

[0152] 3) Preparation of standard chloride ion solution: this part is consistent with Example 2.

[0153] 4) Ion chromatography detection: the instrument parameter settings were consistent with those of Example 1, and the measured chloride ion concentration and the corresponding characteristic peak area are shown in Table 3 and Table 12.

[0154] Table 12 Peak area of sample solution

[0155]

[0156] 5) Test result analysis: with standard chloride ion concentration as the abscissa and peak area as the ordinate, the chloride ion standard solution curve is drawn as shown in Figure 12 , and the fitting equation is shown in equation 6;

[0157] S' / (μs·min) = 0.011 + 0.2691 × C / (mg / L) Equation 6

[0158] Wherein, S' represents the characteristic peak area of chloride ion, C is the chloride ion concentration of the standard solution, and the linear coefficient is 0.9993.

[0159] 6) Chlorine concentration calculation in the sample to be tested: first, the sample peak area 0.366 and the blank solution peak area 0.112 are substituted into equation 2 to calculate the peak area of sample S-3 as 0.254. Then, the peak area of S-3 is substituted into equation 6 to obtain the concentration of chloride ion in the corresponding sample solution as 0.9030 mg / L. Finally, the sample mass 0.506 g and the volume of the liquid to be tested 20 mL are substituted into equation 3 to calculate the chloride ion content in S-3 sample as 35.69 ppm. Example 11

[0160] 1) Cleaning of the sample dissolving tank: this part is consistent with example 1.

[0161] 2) Preparation of sample solution: accurately weigh 10 g of NaOH, and dilute to 250 mL with ultrapure water to obtain a 1 mol / L NaOH solution. Use an analytical balance to weigh the synthetic SiO2 powder numbered S-4 (hydrophobic, specific surface area 115 m 2 / g, particle size 7-40 nm). Place the weighed SiO2 powder in a high-temperature-resistant sample dissolving tank, and measure 20 mL of NaOH solution into the sample dissolving tank, tightly seal and screw, and place it on a constant temperature heating table at 120°C for 180 min. After taking it out, cool it to room temperature, use a sterile injection liquid to remove 12.3 mL of solution, filter it through a 0.22 μm nylon filter, discard the first 2 mL of filtrate, and store the filtered solution in a PFA bottle. The above method obtains a sample solution to be tested with a pH value of 12.86 at 25°C. The solution prepared without adding SiO2 powder sample is the blank solution under the same pH.

[0162] 3) Ion chromatography detection: the instrument parameter settings are consistent with example 1, except that the sample solution to be tested is diluted 10 times this time, and the measured chloride ion concentration and the corresponding characteristic peak area are shown in Table 13. Figure 13 The ion chromatography detection results of the sample solution to be tested (a) and the blank sample (b) of this example are shown.

[0163] Table 13 Peak area of sample solution

[0164]

[0165] 4) Calculation of the concentration of chlorine in the sample to be tested: first, the peak area of the sample 0.710 and the peak area of the blank solution 0.112 are substituted into formula 2 to calculate the peak area of the sample S-4 as 0.598. Then, the peak area of S-4 is substituted into formula 1 to obtain the concentration of chlorine ions in the corresponding sample solution as 2.186 mg / L. Finally, the sample mass 0.506 g and the volume of the liquid to be tested 20 mL are substituted into formula 3 to calculate the content of chlorine ions in S-4 sample as 87.43 ppm.

[0166] The test data of each example are shown in the following table:

[0167]

[0168] As can be seen from the results of examples 1-3 of sample S-1 and examples 7-9 of sample S-3, the RSD of the measured values of the sample by the determination method of the present application is less than 10%, meeting the requirements of analysis and detection. Comparing the average values of examples 1-3 with the results of example 4 shows that the average value of Cl content calculated by the standard curve with background deducted is higher than that calculated without background deduction, and the same trend is shown by comparing the average values of examples 7-9 with the results of example 10. The results show that the standard curve affected by the background peak area value in the standard solution will affect the subsequent quantitative determination of Cl content, and the greater the background peak area value, the greater the influence on the calculation of low content values.

[0169] By comparing the average values of examples 1-3 with the results of example 5, it can be seen that the Cl content value obtained after the sample dissolution tank is washed with ordinary water and then subjected to subsequent alkali digestion is slightly higher than the average value of examples 1-3, indicating that ordinary water washing cannot completely remove the residual attached Cl ions on the inner wall of the sample dissolution tank. In addition, by comparing examples 1-6 and 7-11, it is found that for the test of Cl content in hydrophobic SiO2, the present application can achieve complete digestion of SiO2 and accurate measurement of chlorine content by appropriately prolonging the digestion time, increasing the digestion temperature and increasing the concentration of the alkali solution.

[0170] In addition, it should be understood that, after reading the above description of the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the claims attached hereto.

Claims

1. A method for rapid detection of trace amounts of chloride ions in synthetic silica, characterized in that, The method comprises the following steps: Cleaning the sample dissolving tank: the sample dissolving tank is sequentially subjected to ultrasonic cleaning, high-temperature acid pickling, high-temperature water washing and drying before each use for dissolving synthetic silica, wherein the synthetic silica is hydrophobic silica, the material of the sample dissolving tank is polytetrafluoroethylene (PFA), the ultrasonic cleaning time is 5-10 minutes, the sample dissolving tank is filled with water during the ultrasonic cleaning, the high-temperature acid pickling temperature is 125-135 DEG C, the high-temperature acid pickling time is 180-200 minutes, the acid pickling solution used is a mixed solution of nitric acid and water with a volume ratio of 0.5-1:1, the high-temperature water washing temperature is 125-135 DEG C, and the high-temperature water washing time is 180-200 minutes; the volume of the acid pickling solution used for the high-temperature acid pickling and the volume of the water used for the high-temperature water washing are both not less than 2 / 3 of the volume of the sample dissolving tank; Preparation of sample solution: synthetic silica is accurately weighed and placed in the cleaned sample dissolving tank, an alkaline aqueous solution is added, the ratio of the added mass of the synthetic silica in the sample dissolving tank to the volume of the alkaline aqueous solution is (0.45-0.60 g):(20-25 mL), and a colorless and clear sample solution is obtained by sealed heating digestion; the sealed heating digestion temperature is 100-120 DEG C, and the sealed heating digestion time is 20-180 minutes; Preparation of standard chloride ion solution: a plurality of standard chloride ion solutions with the same volume and a certain concentration gradient are prepared; Ion chromatography detection: the prepared sample solution and the standard chloride ion solution are detected by ion chromatography, and the chloride ion characteristic peak area is recorded; Analysis of test results: a standard curve is drawn by using the chloride ion characteristic peak area of the standard chloride ion solution and the corresponding chloride ion concentration, and an equation of the chloride ion characteristic peak area and the chloride ion concentration is obtained by linear fitting as follows: S'=a+bxC, wherein S' represents the chloride ion characteristic peak area, the chloride ion characteristic peak area S' is the value after deducting the background peak area, the background peak area is the chloride ion characteristic peak area of the standard chloride ion solution with 0 ppm of chloride ion, C is the chloride ion concentration of the standard chloride ion solution, and a and b are standard curve fitting constants; Determination of the chloride ion content in the synthetic silica: Calculation of the actual chloride ion characteristic peak area S of the sample solution: S=S1-S0, wherein S1 represents the chloride ion characteristic peak area of the sample solution, and S0 represents the chloride ion characteristic peak area of the blank solution; the difference between the blank solution and the sample solution is only that the blank solution does not contain synthetic silica, and the rest is the same; The actual chloride ion characteristic peak area of the sample solution is substituted into the equation S'=a+bxC to obtain the chloride ion concentration in the sample solution; The chloride ion content in the synthetic silica is calculated according to the chloride ion concentration in the sample solution.

2. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 1, characterized in that, The volume of the sample dissolving tank is 60-80 mL.

3. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 1, characterized in that, The high-temperature acid pickling temperature is 130 DEG C, and the high-temperature water washing temperature is 130 DEG C.

4. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 1 or 2, characterized in that, The alkaline aqueous solution is a sodium hydroxide aqueous solution, the concentration of sodium hydroxide in the sodium hydroxide aqueous solution is 0.2-1 mol / L, and the amount of the alkaline aqueous solution is 30%-45% of the volume of the sample dissolving tank.

5. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 1, characterized in that, The NaOH solution is diluted in a gradient to obtain a plurality of standard chloride ion solutions with the same volume and a certain concentration gradient. The NaOH solution is diluted in a gradient to obtain a plurality of standard chloride ion solutions with the same volume and a certain concentration gradient.

6. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 5, characterized in that, The preparation of the plurality of standard chloride ion solutions with the same volume and the concentration gradient specifically comprises: diluting the standard chloride ion solution with a chloride ion concentration of 50 mu g / mL by a NaOH solution in a gradient manner to obtain a plurality of standard chloride ion solutions with a chloride ion concentration gradiently distributed in a range of 0-5 mg / L and the same volume.

7. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 5 or 6, characterized in that, The pH of the NaOH solution is 11.5-12.

5.

8. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 1, characterized in that, The ion chromatography test conditions comprise: assembling a negative ion inhibitor, the inhibitor type is AERS-4 mm, the inhibitor current is 50 mA; using an AS19 separation column and an AG19 protection column, the column type is 4 mm*250 mm; the eluent is a 50 mmol / L KOH solution; the column box temperature is 30 DEG C; and the sample injection amount is 25 mu L.

9. The method for rapid detection of trace amounts of chloride ions in synthetic silica according to claim 1, characterized in that, The calculation of the chloride ion content in the synthetic silicon dioxide according to the chloride ion concentration in the sample solution specifically comprises: The chloride ion content in the synthetic silicon dioxide is calculated by substituting the chloride ion concentration in the sample solution into the following formula: w=c*v / M / 1000, wherein w represents the chloride ion content in the synthetic silicon dioxide, the unit is mg / Kg (ppm), c represents the chloride ion concentration in the sample solution, the unit is mg / L, v represents the sample solution volume, the unit is L, and M represents the mass of the synthetic silicon dioxide, the unit is g.

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